thats acc highly exaggerated lol but fair
spoilers:
he lost someone who was dear to him (the tutor yesung hyung) in the past due to an illness. the tutor taught both dojoon and silver haired guy byt dojoon wasnt in love with yesung. after yesung hyung fell sick he asked dojoon to cut off his life support since he was sick of being in pain and he only trusted dojoon to do it.
thats why silver haired calld dojoon a murderer.
and now our dear MC comes along who looos almost exactly like yesung hyung.silver haired only likes him bc he looks like his dead tutor, and projects him onto him.
we're pretty close to the ending actually. in a snippet of the ending, MC finds out about this and says to silver haired "thats why you never called me by my name. thats why u just called me hyung. see? u still cant say my name:

Light haired guy disgusts me more and more